Control device and electric vehicle

ABSTRACT

There is provided a control device configured to perform a collision preventing control based on an output of an obstacle detection unit. A risk level determination unit determines a collision risk level based on a distance between the obstacle and the electric vehicle. A control level adjustment unit adjusts a control level of the collision preventing control based on the collision risk level. The control level adjustment unit lowers the control level when a releasing unit configured to temporarily release the collision preventing control is operated by a driver during the collision preventing control and causes the electric vehicle to display presence of the obstacle.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2019-012133 filed onJan. 28, 2019, including specification, drawings and claims isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a control device and an electricvehicle.

BACKGROUND

In a boarding-ride electric vehicle represented by an electricwheelchair such as a power scooter, a driver is often an elderlydisabled person. Therefore, chances of derailment or falling on gutters,cliffs, dams, railroad crossings, and roads without guard rails andcollisions with obstacles such as road steps, trees, and pedestrians arehigher compared with a healthy person.

For example, the following Patent Document 1 discloses a technique ofattaching a laser radar or a stereo camera to a front side of a hostvehicle (an electric vehicle) to detect an obstacle in front of the hostvehicle. In Patent Document 1, when the obstacle is detected in apredetermined region in a traveling direction of the host vehicle,driving assistance (for example, deceleration control and alarm output)is performed to the host vehicle. A degree of the driving assistance iscontrolled stepwise in accordance with a distance between the hostvehicle and the obstacle.

-   Patent Document 1: Japanese Patent Application Publication No.    2014-226194 A

However, the electric vehicle such as the above-mentioned power scooterhas mobility of traveling on a sidewalk and is treated as a pedestrian.Therefore, compared with a passenger car traveling on a road, asituation is likely to occur in which an obstacle (a person, a bicycle,or the like) comes from right front, leading to an assumed case wherethe electric vehicle travels while avoiding the obstacle coming fromfront. In this case, when the driving assistance described above isstrictly performed in order to prevent a collision with an obstacle,vehicle control such as alarm output, deceleration, and stop would befrequently performed each time an obstacle is present in front.Accordingly, the driver (the user) may feel uncomfortable.

SUMMARY

It is at least one of objects of the present disclosure to provide acontrol device and an electric vehicle that can perform collisionpreventing control in an electric vehicle such as a power scooterwithout causing discomfort to a driver.

According to an aspect of the embodiments of the present disclosure,there is provided a control device configured to perform a collisionpreventing control between an obstacle and an electric vehicle based onan output of an obstacle detection unit which is configured to detectthe obstacle within a predetermined range in a traveling direction ofthe electric vehicle, the control device comprising: a risk leveldetermination unit configured to determine a collision risk levelbetween the obstacle and the electric vehicle based on a distancebetween the obstacle and the electric vehicle; and a control leveladjustment unit configured to adjust a control level of the collisionpreventing control based on the collision risk level and perform thecollision preventing control with the adjusted control level, whereinthe control level adjustment unit lowers the control level when areleasing unit configured to temporarily release the collisionpreventing control is operated by a driver during the collisionpreventing control and causes the electric vehicle to display presenceof the obstacle.

According to another aspect of the embodiments of the presentdisclosure, there is provided an electric vehicle comprising: anobstacle detection unit configured to detect an obstacle within apredetermined range in a traveling direction of the electric vehicle; adisplay unit configured to display presence of the obstacle; a controldevice configured to perform a collision preventing control between theobstacle and the electric vehicle based on an output of the obstacledetection unit; and a releasing unit configured to temporarily releasethe collision preventing control, wherein the control device includes: arisk level determination unit configured to determine a collision risklevel between the obstacle and the electric vehicle based on a distancebetween the obstacle and the electric vehicle; and a control leveladjustment unit configured to adjust a control level of the collisionpreventing control based on the collision risk level and perform thecollision preventing control with the adjusted control level, andwherein the control level adjustment unit lowers the control level whenthe releasing unit is operated by a driver during the collisionpreventing control and causes the display unit to display the presenceof the obstacle.

With the above configuration, it is possible to perform collisionpreventing control in an electric vehicle such as a power scooterwithout causing discomfort to a driver.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an overall perspective view of an electric vehicle accordingto an embodiment;

FIG. 2 is a perspective view of a handle peripheral configuration of theelectric vehicle in FIG. 1 as viewed from a driver;

FIG. 3 is a functional block diagram of the electric vehicle accordingto the present embodiment;

FIG. 4 is a schematic diagram of determination regions for determining acollision risk level of collision preventing control according to thepresent embodiment;

FIG. 5 is a table showing collision preventing control (control levels)for each collision risk level according to the present embodiment;

FIG. 6 is another schematic diagram of the determination regions fordetermining the collision risk level of collision preventing controlaccording to the present embodiment;

FIG. 7 is a flowchart showing an example of vehicle control according tothe present embodiment; and

FIG. 8 is a flowchart showing another example of vehicle controlaccording to the present embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings. In the followingdescription, a power scooter for an elderly person will be described asan example of an electric vehicle to which the present disclosure isapplied, but the application object may be changed without being limitedthereto. For example, the present disclosure may also be applied toother types of electric vehicles such as an electric wheelchair for aperson having a disorder in their body. In terms of direction, a driveris the reference, based on which an arrow FR indicates a vehicle frontside, an arrow RE indicates a vehicle rear side, an arrow UP indicates avehicle upper side, an arrow LO indicates a vehicle lower side, an arrowL indicates a vehicle left side, and an arrow R indicates a vehicleright side, respectively. That is, the direction indicated by the arrowFR is a traveling direction of the vehicle.

An electric vehicle according to the present embodiment will bedescribed with reference to FIGS. 1 to 3. FIG. 1 is an overallperspective view of the electric vehicle according to the presentembodiment. FIG. 2 is a perspective view of a handle peripheralconfiguration of the electric vehicle in FIG. 1 as viewed from thedriver. FIG. 3 is a functional block diagram of the electric vehicleaccording to the present embodiment. The electric vehicle is not limitedto the following configuration and may be modified as appropriate.

First, a schematic configuration of an electric vehicle 1 according tothe present embodiment will be described. As shown in FIG. 1, theelectric vehicle 1 is constituted by a power scooter that travels on asidewalk. The driver is often an elderly person and the electric vehicle1 is treated as a pedestrian for legal purposes. Specifically, theelectric vehicle 1 includes a vehicle body 2 in which an exterior coveris attached to a vehicle body frame 2A. The exterior cover includes afloor portion 2B on which the driver places feet, a front cover 2Cdisposed on a front side of the vehicle body, and a rear cover 2Ddisposed on a rear side of the vehicle body.

The vehicle body frame 2A constitutes an overall frame part and extendsin a front-rear direction. A pair of left and right front wheels 3 aredisposed on the front side of the vehicle body 2. A pair of left andright rear wheels 4 are disposed on the rear side of the vehicle body 2.A handle unit 10 that allows the vehicle to be steered is disposed overthe front wheels 3.

The front wheels 3 and the handle unit 10 are coupled by a steeringshaft (not shown). The steering shaft extends up and down. As will bedescribed in detail below, the steering shaft is provided with asteering sensor 27 (see FIG. 3) that detects a steering angle of ahandlebar 11.

The periphery of the steering shaft is covered with a leg shield 7. Theleg shield 7 constitutes a part of the exterior cover and rises upwardfrom a front portion of the vehicle body. The leg shield 7 has afunction as a windshield that protects the periphery of the feet of thedriver seated on a seat 8, which will be described below, so that windor the like does not directly hit the periphery of the feet.

A front basket 6 is disposed in front of the leg shield 7. The frontcover 2C is provided below the front basket 6 to cover the front wheels3 from above. As will be described in detail below, a camera 28 isprovided on a front surface of the front cover 2C as an obstacledetection unit that detects an obstacle within a predetermined range inthe traveling direction of the electric vehicle 1. The camera 28includes an imaging unit such as a stereo camera or a three-dimensionaldistance image camera and has a predetermined imaging range within thepredetermined range in the traveling direction. In the presentembodiment, the predetermined range in a front side in the travelingdirection is defined as the detection range (the imaging range) of theobstacle, but the present disclosure is not limited thereto. Forexample, not only the front side but also a lateral side and a rear sidemay be set as the predetermined detection range.

The seat 8 for the driver is disposed over a rear portion of the vehiclebody 2. The seat 8 includes a seat cushion 8A on which the driver sits,a seatback 8B that constitutes a backrest of the driver, and a pair ofleft and right armrests 8C. The seatback 8B extends upward from a rearend of the seat cushion 8A. The armrests 8C are provided on two sideportions of the seatback 8B.

A motor 9 and a battery (not shown) for the rear wheels 4 are disposedbelow the seat 8. The motor 9 drives the rear wheels 4 via adifferential device (not shown). The motor 9 is driven by electric powerof the battery. The motor 9 and the battery are covered with the rearcover 2D. In addition to the motor 9 and the battery, various electricalcomponents such as a control device 30 to be described below and avehicle speed sensor 29 (see FIG. 3) that detects a vehicle speed of theelectric vehicle 1 are disposed inside the rear cover 2D.

Next, a detailed configuration of the handle unit 10 will be described.The handle unit 10 is rotated by the driver seated on the seat 8. Asshown in FIG. 2, the handle unit 10 includes a pair of left and righthandlebars 11 held by the driver and a switch box 12 in which variousoperation switches are disposed.

The pair of handlebars 11 protrude from left and right side surfaces ofthe switch box 12 and are bent in a substantially U shape in a planview. In addition, rearview mirrors 13 are disposed at right and leftcorners of the switch box 12, separately.

The switch box 12 is disposed in the middle of the entire handle unit10. The switch box 12 is equipped with an operation device, a displaydevice, and the like that are necessary for driving the electric vehicle1. Specifically, a power switch 14 is disposed in the middle of a nearupper surface of the switch box 12. The power switch 14 is switchedbetween an ON position and an OFF position by rotation operation. Whenthe power switch 14 is operated to the ON position, power of the vehicleis turned on, and when the power switch 14 is operated to the OFFposition, the power of the electric vehicle 1 is turned off.

A pair of accelerator levers 15 are provided on near right and leftsurfaces of the switch box 12. The accelerator levers 15 extend towardsoutside the vehicle from side surfaces of the switch box 12 in vicinityof grip portions of the handlebars 11. The accelerator levers 15 may beoperated by being pressed downward from an initial position. Theaccelerator levers 15 perform acceleration in a traveling direction thatis selected by a traveling direction switching switch 17 to be describedbelow. When the accelerator levers 15 are pressed, the electric vehicle1 travels in a predetermined direction, and when hands are released fromthe accelerator levers 15, a brake is applied to the motor 9 to stop theelectric vehicle 1.

A brake lever 16 is provided on a side surface of a front left corner ofthe switch box 12. The brake lever 16 protrudes leftward and is backwardrotatable from an initial position with its base end serving as astarting point. The brake lever 16 functions as a brake when theelectric vehicle 1 is pushed through hands and functions as a parkingbrake when the electric vehicle 1 is parked.

The switch box 12 is further provided with, on the upper surfacethereof, the traveling direction switching switch 17, a winker switch18, an alarm switch 19, a speed adjustment knob 20, a display unit 21,an audio switch 22, a distance reset switch 23, a forward confirmationlamp 25, and a rearward confirmation lamp 26.

The traveling direction switching switch 17 is constituted by a toggleswitch that is tiltable in the front-rear direction. The travelingdirection switching switch 17 switches the traveling direction of thevehicle to forward or rearward. The traveling direction switching switch17 is rotatable between a forward position indicating forward movementand a rearward position indicating rearward movement. The forward andrearward positions of the traveling direction switching switch 17 areindicated by Pf and Pr in FIG. 2. Pn located between Pf and Pr indicatesan intermediate position (a neutral position).

A pair of left and right winker switches 18 are provided. When the leftwinker switch 18 is operated, a left turn is signaled, and when theright winker switch 18 is operated, a right turn is signaled.

The alarm switch 19 is constituted by a push-button switch. When thealarm switch 19 is pressed, an alarm sound is issued from a speaker 24.

The speed adjustment knob 20 is a dial operation unit and is disposedsubstantially in the middle of the upper surface of the switch box 12.By operating the speed adjustment knob 20, a maximum speed in theforward movement is adjustable within a predetermined speed range. Forexample, the maximum speed of the electric vehicle 1 is adjustablewithin a range of 2 km/h to 6 km/h.

The display unit 21 is constituted by a display that displayspredetermined information on the electric vehicle 1 in a timely mannerand is disposed in the middle of a front side of the upper surface ofthe switch box 12. The display unit 21 displays, for example, atraveling speed, a traveling distance (a trip meter), and a chargingstate of the battery. As will be described in detail below, the displayunit 21 displays a warning when the electric vehicle 1 may collide withan obstacle in front.

The audio switch 22 is constituted by a push-button switch and sets anaudio guidance function on or off.

The distance reset switch 23 is constituted by a push-button switch. Thedistance reset switch 23 is operated to reset the traveling distancedisplayed on the display unit 21 to zero.

The forward confirmation lamp 25 is turned on when the travelingdirection switching switch 17 is set to the forward position and theelectric vehicle 1 may move forward. On the other hand, the rearwardconfirmation lamp 26 is turned on when the traveling direction switchingswitch 17 is set to the rearward position and the electric vehicle 1 maymove backward.

The speaker 24 is provided on a near lower surface of the switch box 12.The speaker 24 issues audio guidance or an alarm. Arrangement locationsof the various components mounted on the switch box 12 are not limitedto the examples described above and may be modified as appropriate.

Next, the control device 30 included in the electric vehicle 1 will bedescribed with reference to FIG. 3. As shown in FIG. 3, the controldevice 30 collectively controls operation of the entire vehicleincluding various configurations of the electric vehicle 1. The controldevice 30 includes a processor that executes various types ofprocessing, a memory, and the like. The memory is constituted by astorage medium such as a Read Only Memory (ROM) and a Random AccessMemory (RAM) depending on application. The memory stores, for example, acontrol program that controls the above-described variousconfigurations.

As described above, electric signals output from the variousconfigurations of the electric vehicle 1 are transmitted to the controldevice 30. For example, an image from the front of the electric vehicle1 imaged by the camera 28 is output to the control device 30. Thecontrol device 30 calculates a distance to an obstacle in front of thevehicle based on the image.

A detection value of the vehicle speed sensor 29 and a detection valueof the steering sensor 27 are output to the control device 30. Thecontrol device 30 calculates the traveling speed of the electric vehicle1 and the steering angle of the steering wheel unit 10 based on thesedetected values.

When an obstacle is detected in the front side in the travelingdirection based on such information (output), the control device 30according to the present embodiment performs collision preventingcontrol to avoid a collision between the obstacle and the host vehicle(the electric vehicle 1). As will be described in detail below, examplesof the collision preventing control by the control device 30 include (1)displaying a warning on the display unit 21, (2) issuing an alarm by thespeaker 24, (3) controlling the motor 9 to perform braking, and thelike.

An example of a control device of an electric vehicle for an elderlyperson in the related art includes such a device in which a devicecapable of measuring a three-dimensional shape, for example, a distanceimage camera, is attached to the electric vehicle. With such an electricvehicle, a failure due to unevenness of a traveling destination isdetected, a driver is notified, and vehicle control (vehicle speedcontrol such as deceleration and stop, steering direction control, andthe like) determined by a distance from an obstacle, a vehicle speed, orthe like is performed.

According to such control, chances of collisions of the vehicle with anobstacle can be reduced for the safety of the driver. However, excessivevehicle control may impair usability. When an obstacle that does notneed to be detected is detected, unintended behavior of a user (thedriver) is assumed to be caused.

Accordingly, it is desirable to carry out collision preventing controlin an electric vehicle such as a power scooter without causingdiscomfort to a driver. In the present embodiment, the camera 28 isprovided as an obstacle detection unit that detects an obstacle in frontof the electric vehicle 1 in the traveling direction. The control device30 performs predetermined collision preventing control based on anoutput of the camera 28. As described above, examples of the collisionpreventing control include (1) displaying a warning on the display unit21, (2) issuing an alarm by the speaker 24, (3) controlling the motor 9to perform braking, and the like.

The electric vehicle 1 further includes a cancel switch 33 as areleasing unit that temporarily releases the above-described collisionpreventing control by operation of the driver. The cancel switch 33 isprovided, for example, in the switch box 12. The cancel switch 33 isconstituted by a push-button switch. The cancel switch 33 temporarilyreleases (cancels) the collision preventing control by being operated bythe driver during the collision preventing control.

The control device 30 includes a risk level determination unit 31 thatdetermines a collision risk level between an obstacle and the electricvehicle 1 based on a distance therebetween, and a control leveladjustment unit 32 that adjusts a control level of the collisionpreventing control based on the collision risk level and performs thecollision preventing control with the adjusted control level.

The risk level determination unit 31 determines the collision risk levelbased on a risk level region to which the obstacle belongs among aplurality of risk level regions (which may also be referred to asdetermination regions) preliminarily determined in accordance with thedistance to the host vehicle within the imaging range of the camera 28in the front side in the traveling direction of the electric vehicle 1.

When the cancel switch is operated by the driver during the collisionpreventing control, the control level adjustment unit 32 lowers thecontrol level of the collision preventing control described above andcauses the display unit 21 to display presence of the obstacle. Forexample, a warning prompting the presence of the obstacle is displayedon the display unit 21.

According to these configurations, when the driver operates the cancelswitch 33 to temporarily release the collision preventing control duringthe collision preventing control, it is possible to prevent unnecessarycollision preventing control by lowering the control level. At thattime, the presence of the obstacle is displayed on the display unit 21.By doing so, the presence of the obstacle can be recognized again(recalled) by the driver even if the relatively elderly driver isdistracted from the presence of the obstacle after operating the cancelswitch 33. Therefore, it is possible to appropriately perform thecollision preventing control and ensure the safety of the driver withoutcausing discomfort to the driver.

The risk level determination unit 31 determines the collision risk levelbased on the distance between the obstacle and the electric vehicle 1and an expected path of the electric vehicle 1. After the operation ofthe cancel switch 33 by the driver, the control level adjustment unit 32resumes the collision preventing control on a condition that thecollision level is lowered.

According to this configuration, after the driver operates the cancelswitch 33, the collision preventing control is performed again when thecollision risk level is lowered by taking a retreat action from theobstacle via some operation relative to the obstacle. Therefore, evenwhen the driver forgets the fact of temporarily operating the cancelswitch 33, the collision preventing control can be automatically resumedand the safety of the driver can be further enhanced.

In the above example, the control device 30 includes the risk leveldetermination unit 31 and the control level adjustment unit 32 as aplurality of functional blocks and the functional blocks are merelyexamples for convenience. The control device 30 is not limited to thesefunctional blocks and may include other functional blocks. The controldevice 30 does not have to explicitly include these functional blocks.The control device 30 may comprehensively perform various types ofcontrol described above. That is, the control device 30 maycomprehensively implement functions of the risk level determination unit31 and the control level adjustment unit 32.

Herein a relationship between the collision risk level and the collisionpreventing control according to the present embodiment will be describedwith reference to FIGS. 4 to 6. FIG. 4 is a schematic diagram ofdetermination regions for determining the collision risk level of thecollision preventing control according to the present embodiment. FIG. 5is a table showing the collision preventing control (control levels) foreach collision risk level according to the present embodiment. FIG. 6 isanother schematic diagram of the determination regions for determiningthe collision risk level of the collision preventing control accordingto the present embodiment.

As shown in FIG. 4, the electric vehicle 1 serving as the host vehicleis traveling in the middle of a sidewalk W extending forward andbackward. The left-right width of the sidewalk W is sufficiently largerthan the left-right width of the electric vehicle 1. The camera 28 (seeFIGS. 1 and 3) has a predetermined imaging range A in front of theelectric vehicle 1 with a gap G that is a blind area part separating therange A from the host vehicle. The imaging range A has a trapezoidalshape in a plan view in which the left-right width increases toward thefront. The imaging range A is divided into a plurality of regions eachconstituting the above-described risk level region. The imaging range Ais divided into six regions according to the distance from the electricvehicle 1. Specifically, the imaging range A includes regions A1 to A4in front of the electric vehicle 1 that have a rectangular shape in aplan view and show the expected path of the host vehicle, and a pair ofright and left right triangular regions A0 on two sides of the regionsA1 to A4.

The rectangular regions A1 to A4 are arranged side by side in afront-rear direction of the sidewalk W and are the regions A1, A2, A3,and A4 as approaching the host vehicle from a distant location.Left-right widths of the regions A1 to A4 are preferably substantiallythe same as or larger than the left-right width of the host vehicle.

In the present embodiment, the imaging range A divided into the regionsA0 to A4 is stored (set) in the control device 30 in advance. Thecontrol device 30 (the risk level determination unit) determines thecollision risk level based on a position of the obstacle in front of thehost vehicle within the imaging range A.

The collision risk level decreases as the distance between the obstacleand the electric vehicle 1 increases. This is because chances ofcollisions with the obstacle decrease as the obstacle moves away fromthe electric vehicle 1. For example, in FIG. 4, the collision risk levelof a region outside the imaging range A of the camera 28 is LV0.Further, the collision risk level of the regions A0 and A1 is LV1.Collision risk levels of the regions A2 to A4 are LV2 to LV4,respectively. In this way, the collision risk level increases asapproaching the electric vehicle 1.

In the present embodiment, a type of the collision preventing control tothe host vehicle changes according to the determined collision risklevel (the control level is adjusted). As shown in FIG. 5, when thecollision risk level is LV0, that is, when the obstacle is outside theimaging range A of the camera 28, the control level is zero, whichrefers to a normal state. In this case, the collision preventing controlis not performed since no influence would be applied to traveling of theelectric vehicle 1.

When the collision risk level is LV1, that is, when the obstacle is inthe region A0 or the region A1, the control level is one, which refersto a warning displayed state. As the specific control content, a warningis displayed on the display unit 21 to prompt the driver to payattention. This is based on an idea that a display only would besufficient since the obstacle is at a relatively distant positionrelative to the host vehicle. As an example of the warning, it iseffective to display a direction, a type, and the like of the obstacle.

When the collision risk level is LV2, that is, when the obstacle is inthe region A2, the control level is two, which refers to an alarmnotified state. As the specific control content, a warning is displayedon the display unit 21, and an alarm sound is further issued from thespeaker 24 to prompt the driver to pay attention. This is based on anidea of notifying the driver of danger by adding an alarm by audio sincethe obstacle is located closer to the host vehicle as compared with thecase of the control level 1. As an example of the alarm, audio guidancesuch as “please pay attention” or a buzzer sound is effective.

When the collision risk level is LV3, that is, when the obstacle is inthe region A3, the control level is three, which refers to adeceleration recommended state. As the specific control content, theelectric vehicle 1 is decelerated in addition to the content of thecontrol level 2. This refers to an idea that, since the obstacle is evencloser to the host vehicle as compared with the case of the controllevel 2, only the alarm display plus the warning issue is insufficientand deceleration control is also performed to avoid a collision. It ismore effective to set the alarm to be louder than that of the controllevel 2 and advance its issuance cycle.

When the collision risk level is LV4, that is, when the obstacle is inthe region A4, the control level is four, which refers to a stoprecommended state. As the specific control content, the electric vehicle1 is stopped instead of the deceleration control of the control level 2.This refers to an idea of stopping the host vehicle to avoid thecollision reliably since the obstacle is further closer to the hostvehicle as compared with the case of the control level 3 and a collisionmay occur accompanying the deceleration. It is more effective to set thealarm to be louder than that of the control level 3 and advance itsissuance cycle.

In this way, it is possible to implement more appropriate collisionavoidance to the host vehicle by properly changing the control levelaccording to the collision risk level. That is, the control levelincreases as the collision level increases. The variation of thecollision risk level and the control level is not limited to the aboveexample and may be changed as appropriate. For example, when a pluralityof different obstacles in the same direction are detected, an obstaclethat is closer to the host vehicle may be given priority. When there area plurality of obstacles in another direction, an obstacle that isclosest to the host vehicle may be given priority. As described above,by setting the collision risk level of the region A0 outside the regionsA1 to A4 that are the expected path of the host vehicle to LV1, it ispossible to provide a safe state without impairing comfortable drivingperformance for the driver. The region A0 may be alerted when, forexample, there is a gutter on a side of the sidewalk W.

After the collision preventing control is performed, the driver mayavoid the obstacle or release the collision preventing control. Forexample, when the driver visually recognizes an obstacle, it is assumedthat the driver feels uncomfortable about the collision preventingcontrol (unnecessary alarm or deceleration). Therefore, the presentembodiment provides the following control release method.

(1) Obstacle Out of Predetermined Region Due to Steering Operation ofDriver

For example, in a case of an obstacle in the region A2 of FIG. 4, theregions A0 to A4 change in accordance with the steering angle of theelectric vehicle 1 when the driver performs a steering operation, as isshown in FIG. 6. In FIG. 6, by switching the handlebars 11 to the right,the regions A1 to A4, which are the expected path of the host vehicle,change in a curved shape toward the right side. As a result, an obstacleB exits the region A2 and now belongs in the region A0. In this case,the control device 30, instead of issuing an alarm as the collisionpreventing control of the control level 2, lowers the control level toone and performs control to display only a warning on the display unit21 since the obstacle B belongs to the region A0. Accordingly, an alarmby audio is released and the discomfort to the driver can be eliminated.

(2) Pressed Cancel Switch 33

When the collision risk level is LV2 to LV4, the driver may temporarilyrelease the collision preventing control by operating the cancel switch33. In this case, the control device 30 resumes the collision preventingcontrol on a condition that the collision risk level is equal to orlower than LV1. When the collision risk level is LV2 or LV3, thecollision preventing control can be canceled even when the host vehicleis traveling. When the collision risk level is LV4, the collisionpreventing control cannot be canceled until the host vehicle is stopped.Accordingly, discomfort to the driver can be eliminated.

(3) No Intention of Traveling

When the driver stops traveling while the collision risk level is LV1 toLV3, the control level is set to one or the collision preventing controlis ended. This is because it can be said that chances of collisions withan obstacle are reduced by stopping the host vehicle.

(4) Completely Turned Off Collision Preventing Control

When the driver has confidence in driving and does not want to use anycollision preventing control, the collision preventing control may becompletely stopped (that is, fixing the collision risk level always toLV0) by long-pressing the cancel switch 33. Complete cancellation of thecollision preventing control is set only at the time of stop of the hostvehicle.

In this way, in the present embodiment, the driver can avoid a collisionbefore the vehicle is stopped, for example, by performing the collisionpreventing control using the expected path of the electric vehicle 1,the imaging range of the camera 28, and the distance between theobstacle and the host vehicle. Therefore, it is possible to perform asmooth operation without deceleration or stop due to unnecessary vehiclecontrol. Further, it is possible to ensure the safety of the driver inadvance by warning the driver with the display unit 21 or the like ofthe presence of the obstacle in the front side in the travelingdirection of the host vehicle while traveling. Further, the driver canavoid the obstacle by themselves before the vehicle is stopped bydistinguishing the collision risk level and the control level inaccordance with the position of the obstacle so that excessive vehiclecontrol can be prevented. In addition, it is possible to prompt thedriver to avoid the obstacle since the driver is notified of a dangerlevel stepwise.

Next, a control flow according to the present embodiment will bedescribed with reference to FIGS. 7 and 8. FIGS. 7 and 8 show examplesof the control flow according to the present embodiment. In thefollowing flows, unless otherwise specified, operation (calculation,determination, and the like) is performed mainly by the control device30. In control flows shown in FIGS. 7 and 8, it is assumed that theprocessing from “start” to “end” is repeated at predetermined timeintervals.

First, a flow of the collision preventing control will be described. Asshown in FIG. 7, when the control is started, in step ST101, the controldevice 30 determines whether an obstacle is detected. For example, thecontrol device 30 can determine whether the obstacle is detected basedon whether the obstacle is in the imaging range A of the camera 28. Whenthe obstacle is detected (step ST101: YES), the process proceeds to stepST102. When no obstacle is detected, that is, no obstacle is within theimaging range A (step ST101: NO), the collision preventing control isnot necessary, the collision risk level is LV0, and the control isended.

In step ST102, the control device 30 calculates the collision risklevel. Specifically, the risk level determination unit 31 determines(calculates) the collision risk level based on a region to which theobstacle belongs among the regions A0 to A4, in addition to the distancebetween the obstacle and the host vehicle, the steering angle of thehandlebars 11, the vehicle speed, and the like. Then, the processproceeds to step ST103.

In step ST103, the control device 30 performs the collision preventingcontrol at a control level corresponding to the determined collisionrisk level. The specific control content is as described above.Accordingly, the control ends.

Next, a temporary release and resumption flow of the collisionpreventing control will be described. In FIG. 8, it is assumed that somecollision preventing control is performed in advance. As shown in FIG.8, when the control is started, in step ST201, the control device 30determines whether the cancel switch 33 was operated (pressed) by thedriver. When the cancel switch 33 was operated (step ST201: YES), theprocess proceeds to step ST202. When the cancel switch 33 is notoperated (step ST201: NO), the control is ended.

In step ST202, the control device 30 determines whether the collisionpreventing control of the control level 4 is being performed. When thecollision preventing control of the control level 4 is being performed(step ST202: YES), the process proceeds to step ST203. When thecollision preventing control of the control level 4 is not beingperformed (step ST202: NO), the process proceeds to step ST207.

In step ST203, the control device 30 determines whether the electricvehicle 1 is stopped. When the electric vehicle 1 is stopped (stepST203: YES), the process proceeds to step ST204. When the electricvehicle 1 is not stopped (step ST203: NO), the processing of step ST203is repeated. That is, step ST203 is a step of waiting until the vehicleis stopped by automatic braking.

In step ST204, the control device 30 lowers the control level to one andperforms the collision preventing control. Then, the process proceeds tostep ST205.

In step ST205, the control device 30 determines whether the collisionrisk level is equal to or lower than LV1. When the collision risk levelis equal to or lower than LV1 (step ST205: YES), the process proceeds tostep ST206. When the collision risk level is not equal to or lower thanLV1 (step ST205: NO), the processing of step ST205 is repeated. That is,step ST205 is a step of waiting for the collision risk level to decreaseto LV1 by an avoidance action of the driver themselves.

In step ST206, the control device 30 resumes the temporarily releasedcollision preventing control and performs normal vehicle control. Then,the control ends.

In step ST207, the control device 30 determines whether the collisionpreventing control of the control level 2 or 3 is being performed. Whenthe collision preventing control of the control level 2 or 3 is beingperformed (step ST207: YES), the process proceeds to step ST204 toimmediately lower the control level to perform the collision preventingcontrol of the control level 1. When the collision preventing control ofthe control level 2 or 3 is not being performed (step ST207: NO), thecollision preventing control of the current control level 1 is beingperformed and the control is ended as it is.

In this way, in the present embodiment, after being temporarilycanceled, the collision preventing control is automatically resumed onthe condition that the control level is lowered. According to thisconfiguration, it is possible to prevent the driver from forgetting toresume the collision preventing control. Since the collision preventingcontrol is automatically resumed, manual resumption is not necessaryeach time the driver operates the cancel switch 33. This is because itwould be troublesome for the driver to manually resume the collisionpreventing control each time. For example, when obstacles (pedestrians,bicycles, or the like) always come in front at a busy place, thecollision preventing control is canceled and resumed each time thedriver passes an obstacle after the above control is canceled once,making the operation troublesome.

When the control level is in the alarm notified state (2) or thedeceleration recommended state (3), the control level adjustment unit 32immediately sets the control level to the warning displayed state (1),and when the control level is in the stop recommended state (4), thecontrol level is set to the warning displayed state (1) on the conditionthat the electric vehicle is stopped. In this way, when the controllevel is two or three, the collision preventing control can be canceledeven during traveling of the vehicle, whereas when the control level isfour, the collision preventing control can be canceled under thecondition that the vehicle is stopped. This is for ensuring avoidancetime for prompting the avoidance action by the driver and a brakingdistance of the electric vehicle 1 because the obstacle is very close tothe host vehicle when the control level is four.

As described above, according to the present embodiment, it is possibleto perform collision preventing control in the electric vehicle 1 suchas a power scooter without causing discomfort to the driver.

The above embodiment describes the camera 28 as an example of theobstacle detection unit, but the present disclosure is not limitedthereto. A sensor such as a laser radar may be adopted as the obstacledetection unit. In this case, it is preferable for the laser radar tohave a predetermined illuminating range in front of the vehicle.

The above embodiment describes a case where the camera 28 has theimaging range A having a trapezoidal shape in a plan view in the frontside in the traveling direction of the electric vehicle 1, but thepresent disclosure is not limited thereto. For example, anomnidirectional camera having a circular imaging range in a plan viewmay be used.

In the above embodiment, the division method of the plurality of risklevel regions may be changed as appropriate. The number and arrangementlocations of the regions are not limited to those described above, and aplurality of regions may be divided in a road width direction(left-right direction), for example. Further, an overlap part may beprovided at a boundary of adjacent regions, and hysteresis may beprovided during control switching. Accordingly, frequent controlswitching can be prevented.

The above embodiment describes a person or a bicycle as an example ofthe obstacle, but the present disclosure is not limited thereto. Theobstacle may include anything that hinders the traveling of the electricvehicle 1 such as a step or a wall.

Although the present embodiment and the modification have beendescribed, they may be combined in whole or in part as anotherembodiment of the present disclosure.

Embodiments of the present disclosure are not limited to the aboveembodiment and various changes, substitutions and modifications may bemade without departing from the scope of the technical idea of thepresent disclosure. Further, the present disclosure may be implementedby use of other methods as long as the technical concept of the presentdisclosure can be implemented by the methods through advance oftechnology or other derivative technology. Accordingly, the presentinvention cover all embodiments that may fall within the scope of thetechnical idea of the present invention.

As described above, the present disclosure has such an effect thatcollision preventing control can be performed in an electric vehiclesuch as a power scooter without causing discomfort to a driver, and isparticularly useful for a control device and an electric vehicle.

What is claimed is:
 1. A control device configured to perform acollision preventing control between an obstacle and an electric vehiclebased on an output of an obstacle detection unit which is configured todetect the obstacle within a predetermined range in a travelingdirection of the electric vehicle, the control device comprising: a risklevel determination unit configured to determine a collision risk levelbetween the obstacle and the electric vehicle based on a distancebetween the obstacle and the electric vehicle; and a control leveladjustment unit configured to adjust a control level of the collisionpreventing control based on the collision risk level and perform thecollision preventing control with the adjusted control level, whereinthe control level adjustment unit lowers the control level and causesthe electric vehicle to display presence of the obstacle when areleasing unit configured to temporarily release the collisionpreventing control is operated by a driver during the collisionpreventing control.
 2. The control device according to claim 1, whereinthe risk level determination unit determines the collision risk levelbased on the distance between the obstacle and the electric vehicle andan expected path of the electric vehicle, and wherein when the releasingunit is operated, the control level adjusting unit resumes the collisionpreventing control on a condition that the collision risk level islowered.
 3. The control device according to claim 1, wherein thecollision risk level decreases as the distance between the obstacle andthe electric vehicle increases.
 4. The control device according to claim1, wherein the risk level determination unit determines the collisionrisk level based on a determination region to which the obstacle belongsamong a plurality of determination regions preliminarily determined inaccordance with a distance from the electric vehicle within a detectionrange of the obstacle detection unit.
 5. The control device according toclaim 4, wherein the plurality of determination regions change inaccordance with a steering angle of the electric vehicle.
 6. The controldevice according to claim 1, wherein the control level increases as thecollision risk level increases, and wherein the control level includes:a warning displayed state in which a warning is displayed on a displayunit; an alarm notified state in which an alarm sound is issued inaddition to displaying the warning; a deceleration recommended state inwhich deceleration of the electric vehicle is performed in addition todisplaying the warning and issuing the alarm sound; and a stoprecommended state in which the electric vehicle is stopped instead ofdecelerated in the deceleration recommended state.
 7. The control deviceaccording to claim 6, wherein if the control level is in the alarmnotified state or the deceleration recommended state when the releasingunit is operated, the control level adjustment unit immediately sets thecontrol level to the warning displayed state, and if the control levelis in the stop recommended state when the releasing unit is operated,the control level is set to the warning displayed state on the conditionthat the electric vehicle is stopped.
 8. An electric vehicle comprising:an obstacle detection unit configured to detect an obstacle within apredetermined range in a traveling direction of the electric vehicle; adisplay unit configured to display presence of the obstacle; a controldevice configured to perform a collision preventing control between theobstacle and the electric vehicle based on an output of the obstacledetection unit; and a releasing unit configured to temporarily releasethe collision preventing control, wherein the control device includes: arisk level determination unit configured to determine a collision risklevel between the obstacle and the electric vehicle based on a distancebetween the obstacle and the electric vehicle; and a control leveladjustment unit configured to adjust a control level of the collisionpreventing control based on the collision risk level and perform thecollision preventing control with the adjusted control level, andwherein the control level adjustment unit lowers the control level andcauses the display unit to display the presence of the obstacle when thereleasing unit is operated by a driver during the collision preventingcontrol.